The present invention relates to a tape cartridge having a tape loading pocket in the center of a front face of a main case and a tape protecting front cover provided on the main case for covering the outer front face of the pocket.
In this type of tape cartridge, a tape reel incorporated in the main case sometimes rotates improperly upon reception of external impact, and a tape sagging and protruding toward the front face of the case main body adheres tightly to the static-charged back side of the front wall of the front cover.
In the case where such tape adhesion phenomenon occurs, the tape is extracted together with the front wall of the front cover from the tape reel when a tape cartridge is loaded onto a tape deck and the front cover is opened by a upward rotation. Consequently, a so-called jamming phenomenon occurs at the time of tape loading, and this causes the deck inoperable, as well as tape damage and ejection failure of the tape cartridge from the tape deck. Such failure may be eliminated by, for example, forming the front cover from resin materials containing antistatic agents, which increases manufacturing costs of the tape cartridge.
The back side of the front wall of the front cover is generally polished to be a smooth surface, i.e., mirror polished. As a result, a small amount of moisture, if attaching to the back side of the front cover due to the use environment of the tape cartridge, causes the tape to tightly adhere to the back side of the front cover in a similar manner. In this case, this problem cannot be solved simply by forming the front cover from resin materials containing antistatic agents.
In this point of view, the basic purpose of the present invention is to make the back side of the front cover uneven so as to prevent the phenomenon that the tape adheres to the back side of the front cover due to the influence of static charge and moisture. As prior arts to aim a similar purpose, there are JP H8-293182 A (Paragraph No. 0022, FIGS. 5, 12) and JP H7-147075 A (Paragraph No. 0031, FIGS. 2, 6).
In JP H8-293182 A, recess portions having backward openings are formed on the back side of the front wall of the front cover to have a stepped surface, so that a facing distance to the tape is increased for the recess size of the recess portion, which prevents tape adhesion to the back side of the front wall.
In JP H7-147075 A, protruding portions are formed on the back side of the front wall to decrease a contact area between the tape and the back side in order to prevent tape adhesion. The protruding portions in this case are formed to have a square cross section having a flat top end face. The protruding portions may be formed to have a triangle cross section (see FIG. 12 in JP H8-293182 A and FIG. 2 in JP H7-147075 A).
In the structure disclosed in JP H8-293182 A, when the tape cartridge receives dropping impact and the like, a tape largely sags and protrudes to the inner face of the recess portion, thereby causing the tape to adhere to the inner face of the recess portion. More particularly, in the structure for increasing a facing distance size to the tape by a recess size of the recess portion, when the tape sags and protrudes beyond the facing distance size, the tape is still in danger of adhering to the inner face of the recess. In the structure disclosed in JP H7-147075 A, if an area of the flat top end face is large, then the tape is in danger of adhering to the top end face. In the structure that the protruding portion has an angular corner section such as square cross sections and triangle cross sections, the tape is likely to suffer a damage by touching the protruding portion and cause recording and reproducing failure.